COMMERCIAL VEHICLE TYRE

Abstract

A commercial vehicle tire of a radial type of construction with a cross-sectional height of 135 mm to 200 mm, a load index of 121 to 154, a radial-ply casing with at least one casing ply composed of steel cords embedded in rubber and with bead regions with bead cores and bead fillers around which the casing ply runs so as to form turn-ups. The casing ply is reinforced with steel cords of the construction 1+6, wherein the core filament (1) has a diameter (d.sub.1) of 0.19 mm to 0.22 mm and the ply filaments (2) have coinciding diameters (d.sub.2) of 0.17 mm to 0.20 mm, wherein the diameter (d.sub.2) of the ply filaments (2) is less than the diameter (d.sub.1) of the core filament (1) by at least 0.01 mm and wherein, at the crown of the tire, the steel cords are arranged in the casing ply with 60 epdm to 75 epdm.

Claims

1.-6. (canceled)

7. A commercial vehicle tire of a radial type of construction with a cross-sectional height of 135 mm to 200 mm, a load index of 121 to 154, a radial-ply casing with at least one casing ply composed of steel cords embedded in rubber and with bead regions with bead cores and bead fillers around which the casing ply runs so as to form turn-ups; wherein the casing ply is reinforced with steel cords of the construction 1+6, and comprised of a core filament and ply filaments, wherein the core filament has a diameter (d1) of 0.19 mm to 0.22 mm and the ply filaments have coinciding diameters (d2) of 0.17 mm to 0.20 mm; wherein the diameter (d2) of the ply filaments is less than the diameter (d1) of the core filament by at least 0.01 mm; and, wherein, at the crown of the tire, the steel cords are arranged in the casing ply with 60 epdm to 75 epdm.

8. The commercial vehicle tire as claimed in claim 7, wherein the diameter (d2) of the ply filaments is less than the diameter (d1) of the core filament by at least 0.02 mm.

9. The commercial vehicle tire as claimed in claim 7, wherein the core filament and the ply filaments have a tensile strength of at least 3200 N/mm.sup.2.

10. The commercial vehicle tire as claimed in claim 7, wherein the ply filaments are twisted around the core filament with a length of lay of 10.0 mm to 14.0 mm.

11. The commercial vehicle tire as claimed in claim 10, wherein the length of lay is 12.5 mm.

12. The commercial vehicle tire as claimed in claim 7, wherein the core filament has a diameter (d1) of 0.20 mm and the ply filaments have a diameter (d2) of 0.175 mm.

Description

[0011] Further features, advantages and details of the invention are now described in more detail on the basis of the single FIGURE,

[0012] FIG. 1, which schematically shows a cross section of a design variant of a steel cord intended for a casing ply of a commercial vehicle tire.

[0013] A commercial vehicle tire designed according to the invention is a commercial vehicle tire of the radial type of construction with a cross-sectional height of 135 mm to 200 mm and a load index of 121 to 154. The commercial vehicle tire has the usual components, such as a profiled tread, a multi-ply breaker belt assembly, in particular reinforced with steel cords, an inner layer, bead regions with bead cores and bead fillers and also a radial-ply casing comprising at least one casing ply reinforced with steel cords. The steel cords of the casing ply run in the radial direction in the sidewalls, in the axial direction radially inside the tread and the breaker belt.

[0014] FIG. 1 shows a cross section of a steel cord particularly suitable for use in the casing ply of commercial vehicle tires designed according to the invention, which has the construction 1+6 and accordingly comprises a single core filament 1 and six ply filaments 2 in contact with the outer side thereof. The ply filaments 2 are twisted in a way known per se in the S or Z direction around the core filament 1, with a length of lay of 10.0 mm to 14.0 mm, preferably of approximately 12.5 mm.

[0015] The core filament 1 and the ply filaments 2 consist of steel of strength classes NT (normal tensile), HT (high tensile) or SHT (super high tensile). Steel filaments of the strength class NT have a tensile strength of 2700 N/mm.sup.2 to 3050 N/mm.sup.2, steel filaments of the strength class HT have a tensile strength of 3050 N/mm.sup.2 to 3330 N/mm.sup.2 and steel filaments of the strength class SHT have a tensile strength of 3350 N/mm.sup.2 to 3650 N/mm.sup.2. In the case of a preferred design, the filaments 1, 2 have a tensile strength of at least 3200 N/mm.sup.2.

[0016] The core filament 1 and the ply filaments 2 each have a substantially circular cross section. The core filament 1 has a diameter d.sub.1 of 0.19 mm bis 0.22 mm, preferably of 0.20 mm. All of the ply filaments 2 have coinciding diameters d.sub.2 of 0.17 mm to 0.20 mm, in particular of 0.175 mm, wherein the diameter d.sub.2 of the ply filaments 2 is less than the diameter d.sub.1 of the core filament 1 by at least 0.01 mm, preferably by at least 0.02 mm. In the case of a preferred design, the steel cord has a core filament 1 with a diameter d.sub.1 of 0.20 mm and six ply filaments 2 with a diameter d.sub.2 of 0.175 mm.

[0017] For producing a casing ply comprising such steel cords, the steel cords are embedded in one of the usual rubberizing mixtures by calendering, wherein the number of steel cords in the unvulcanized calendered casing ply is 90 epdm to 120 epdm (ends per decimeter).

[0018] In the vulcanized commercial vehicle tire as a finished product, the number of steel cords at the crown of the tire or along the equatorial plane of the tire is 60 epdm to 75 epdm, depending on the size of the tire.

LIST OF REFERENCE NUMERALS

[0019] 1 . . . Core filament [0020] 2 . . . Ply filament [0021] d.sub.1, d.sub.2 . . . Diameter